Postinfarction reentrant ventricular tachycardia is an important clinical problem, yet locating the circuit can be problematic (Wit A L. Heart Rhythm 2006; 3:198-200; Garan H. Progress in Cardiovascular Diseases 1996; 38:457-462). Electrical activation mapping, which requires induction of the clinical ventricular tachycardia in the patient, is currently used for pinpointing reentrant circuit location. However, this procedure is often time-consuming and is limited by the fact that clinical tachycardia cannot always be induced and/or it may not be well-tolerated hemodynamically by the patient. Furthermore, in some cases, the relevant clinical reentrant ventricular tachycardia that the patient experiences cannot be induced during electrophysiologic study, in which case it cannot be accurately mapped. Therefore, alternative methods for identifying reentrant circuit location are needed.
In canine postinfarction hearts, the reentrant circuit isthmus has been shown to overlap the thinnest infarct border zone (BZ), and functional block lines tend to coincide with sharper transitions to thicker tissue about the isthmus (Wit A L, et al. Am J Cardiol 1982; 49:166-185; Peters N S, et al. Circulation 1997; 95:988-996). Both the isthmus and the functional block lines tend to remain approximately constant in location during any particular reentrant circuit morphology (Ciaccio E J, et al. J Cardiovasc Electrophysiol. 2004; 15:1293-1301; Ciaccio E J. J Cardiovascular Electrophysiology 2005; 16:646-654).
When multiple reentrant circuit morphologies are inducible in the canine infarct BZ, it has been observed that the isthmus location of most or all of the morphologies coincide, with a difference in isthmus entrance and exit points being the distinguishing characteristic (Ciaccio E J, et al. J Cardiovasc Electrophysiol. 2004; 15:1293-1301; Ciaccio E J. J Cardiovascular Electrophysiology 2005; 16:646-654; and Costeas C. et al. Circulation. 1997; 96:3721-3731). Development of a geometric model relating border zone (BZ) structure to reentry conduction characteristics would allow the prediction of reentrant circuit pattern and characteristics from imaging data of the infarct and border zone, as well as identification of the isthmus and candidate ablation sites in postinfarction patients and in other patients with structural remodeling of heart tissue causing nonviable areas with border zones (BZ) about which recurrent ventricular tachycardia can arise. A need therefore remains for development of such a geometric model.